X-ray photoelectron spectroscopy investigation of substrate surface pretreatments for diamond nucleation by microwave plasma chemical vapor deposition

The effects of surface pretreatments on the nucleation of diamond on silico n substrates have been studied by quantitative X-ray photoelectron spectros copy (XPS), SEM and Raman spectroscopy. The methods of surface pretreatment s including ultrasonic abrasion, scratching, and DC biasing were used for d iamond nucleation enhancement. Diamond films grown by different surface pre treatments and selected intervals in bias-enhanced nucleation were analyzed for the surface composition in the C 1s and Si 2p regions. Before diamond growth XPS analysis showed that the Si substrate surface is covered by a la yer of SiO2 and carbonaceous residue. It was found that methods of surface pretreatment all introduce a substantial amount of carbon species on the su bstrate surface that was the primary reason for the enhancement of diamond nucleation. In the biasing process, it reduced and suppressed the formation of oxide that further contributed to the enhanced nucleation density of di amond, and it was observed that the presence of SiC in the initial stage of nucleation is due to the carbon interaction with the Si substrate. (C) 200 0 Elsevier Science B.V. All rights reserved.